Precision pest control

Former Washington State University scientist Dr. Michio Kise shows the multipurpose autonomous sprayer, under development by Dr. Fran Pierce, to Washington growers at a winter grape meeting.

Using a battery powered all-terrain vehicle, Dr. Fran Pierce has developed a prototype autonomous sprayer for targeted pest control that is ready for testing this year .

Pierce, director of Washington State University’s Center for Precision Agricultural Systems works on a variety of different precision technologies for tree fruit, grapes, and irrigated cropping systems. Pierce said that automated pest control tools have several potential benefits for tree fruit and grape growers—reducing labor costs, improving spray efficiencies, and reducing impact to the environmental and human aspects of pesticides in food systems.

He spent last year working with former WSU scientist Michio Kise to develop a targeted sprayer system that could detect and measure grapevine trunks, maintain continuous pressure for the spray nozzles, and automatically apply a pesticide, such as a trunk barrier spray for cutworm control. While there are other pesticide sprayers with sensors already commercially available, Pierce said that in the future, the targeted sprayer has the capability to simultaneously perform other tasks, such as sucker control with herbicides, fungicide control in the canopy, or applying nutrients in a foliar spray to the leaves. Moreover, with more precise application, it has the potential to reduce the amount of pesticides used.

Applicable to other tasks

"Once we can move the sprayer in the vineyard and have it recognize the target, it could be applicable to other tasks," he said. Pierce looked for system components that were market-ready and commercially available. He put the targeted sprayer on an electric John Deere Gator that has auto steering, although in his field tests, they have not fully used the auto-steer controls. The spray tank and nozzles he used are commercially available.

The brains of the system—computer software that tells the sprayer when and how much to spray—are contained in a personal computer laptop that sits on the Gator. Laser sensors that detect and size the trunks have a 240-degree view.

In the future, Pierce said that the auto-steering system could be utilized to make the unit completely autonomous, with no need for a driver. For now, a driver makes turns, but the Gator steers itself down the row. The Global Positioning System that is part of the system has not been activated, but it could provide GPS maps to show exactly what was sprayed.

"The value is that the autonomous sprayer could be doing five things at the same time, including some constant issues like measuring crop load or scouting for pests," he said.

Pierce said there is much work yet to do to on the prototype, including fine-tuning rates and nozzle pressures for the pesticide sprays, but he’s excited about the prospect of prototype technology that is field ready.

"We have something that can actually go through the field and do the detection," he said.

Pierce received competitive grant funding for the research from WSU’s Emerging Issues Research Initiative.